Abstract

Many animals reside in burrows that may serve as refuges from predators and adverse environmental conditions. Burrow design varies widely among and within taxa, and these structures are adaptive, fulfilling physiological (and other) functions. We examined the burrow architecture of three scorpion species of the family Scorpionidae: Scorpio palmatus from the Negev desert, Israel; Opistophthalmus setifrons, from the Central Highlands, Namibia; and Opistophthalmus wahlbergii from the Kalahari desert, Namibia. We hypothesized that burrow structure maintains temperature and soil moisture conditions optimal for the behavior and physiology of the scorpion. Casts of burrows, poured in situ with molten aluminum, were scanned in 3D to quantify burrow structure. Three architectural features were common to the burrows of all species: (1) a horizontal platform near the ground surface, long enough to accommodate the scorpion, located just below the entrance, 2–5 cm under the surface, which may provide a safe place where the scorpion can monitor the presence of potential prey, predators, and mates and where the scorpion warms up before foraging; (2) at least two bends that might deter incursion by predators and may reduce convective ventilation, thereby maintaining relatively high humidity and low temperature; and (3) an enlarged terminal chamber to a depth at which temperatures are almost constant (±2–4 °C). These common features among the burrows of three different species suggest that they are important for regulating the physical environment of their inhabitants and that burrows are part of scorpions’ “extended physiology” (sensu Turner, Physiol Biochem Zool 74:798–822, 2000).

Notes

Acknowledgments

We thank Stuart Summerfield for the invaluable technical assistance; David Andreen, Golan Bel, and Mike Kirby for their help with calculating burrow tortuosity; Gina and Jacobus Olivier for their incredibly generous hospitality and assistance in the field at Bloukop; Eran Gefen and Yael Lubin for their advice; and three anonymous reviewers for the comments on a previous draft of the manuscript. This research was supported by grant 136/10 from the Israel Science Foundation to BP and Pedro Berliner, Human Frontier Science Program grant RGP0066/2012-TURNER to JST and EM, and by a post-doctoral fellowship from the Jacob Blaustein Center for Scientific Cooperation and a Company of Biologists Travel Grant from the Society of Experimental Biology to AMA. This is paper number 908 of the Mitrani Department of Desert Ecology.

Authors’ contributions

AMA, EM, JST, and BP conceived, designed, and performed the experiments. AMA analyzed the data. LP identified the scorpions. AMA and BP wrote the manuscript and JST and LP edited the manuscript.

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